[Malcolm] has a home security system that uses a series of motion sensors to detect movement in the house. When movement is detected an indicator LED turns on, and a wireless signal is sent to the main control system. So after discovering a nice 3D model of the TARDIS (Time and Relative Dimension in Space) on Thingiverse, he decided to see if he could hack one of his motion sensors to fit inside of it instead.

As it turns out, it was as simple as removing the sensor’s external shell, 3D printing a few support pieces inside of the TARDIS, and soldering on a bright blue LED to replace the dinky indicator light. Simple, but effective!